From the DM article: "The TanDEM-X mission is to generate a global digital elevation model - WorldDEM - of unprecedented quality, accuracy and coverage. This DEM is intended to be the replacement dataset for SRTM and will be available in 2014 for the Earth’s entire land surface - pole to pole. The accuracy of the WorldDEM will surpass that of any satellite-based elevation model available today and will have the following unique features:

Vertical accuracy of 2m (relative) and 10m (absolute)

12m x 12m raster

Global homogeneity

Highly consistent dataset as a result of an initial global data collection window of 2.5 years and the opportunity to continue to collect locally beyond the initial collection period

No need for ground control information due to the high geometric precision of German sensors "